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Patented Nov. 22, 1932 UNITED STATES PATENT OFFICE ELMER C. SCHAGHT, OF TROY, NEW YORK, ASSIGNOR T0 BEER-MANNING- CORPORATION, OF TROY, NEW YORK, A CORPORATION OF MASSACHUSETTS PAPER No Drawing.

The present invention is a. paper-like mate rial consisting essentially of fibers and cork. An object of the invention is to produce a sealing material which will possess to the 0ptimum degree, the qualities of compressibility and re-bound, strength and flexibility, and which also will be resistant to abrasion, oil proof and waterproof. In addition, the sheet material of this invention will be free from objectionable shrinkage and brittleness. I am aware that a paper, produced on a paper making machine and saturated with a plasticizer, such as glycerine, and an adhesive. is well known. Such material, however, does not possess the remarkable flexibility and freedom from cracking of my present invention and has a fundamental and serious defect, in that the compressibility and re-bound obtainable are not satisfactory.

Material consisting of comminuted cork treated by similar agents and then formed into sheets is also old. Such a product, however, although compressible, is brittle, very,

susceptible to dimension changes when subjected to changes in moisture content, and readily tears.

The prior art discloses numerous mixtures of cork, fibersapd various other materials with an adhesive'll But none of the resulting products has a body-consisting essentially, i. e., substantially exclusively, of cork and fiber, the formed web being treated by a binder, or a binder and plasticizer, so that the product possesses the flexibility, tensile strength and resilience of the sheet material of the present-invention. r

The product of this application possesses the fundamental requirement of a sealing material satisfactory for gaskets and packings, namely, a maximum degree of compres sibility and re-bound accompanied by sufficient strength and pliability in the finished web, so that it may be creased and folded without breakin g and without producingpermanent lines of cleavage; it is also characterized. by except onal strength and resistance to tearing and blowing.

In carrying out the invention, I prepare in .a heater or mixer a suitable pulp after the manner and practice of the art of paper Serial No. 581,511.

manufacture, which pulp will comprise inter-mixed fibers and comminuted cork. The pulp so obtained is passed to a paper making machine, either of the cylinder type or the Fourdrinier type. The felted web produced is very lightly calendered and, in fact, calendering may be omitted.

This web is characterized by having a cellular structure, created by the intimate mixture obtained, since the diameter or cross section of the individual fibers is less than the corresponding dimension of the effective cork particles. That is to say, the fibers are so interlaced and the comminuted cork s0 enmeshed in the interlaced fibers that voids are produced throughout the web. The cork particles, therefore, act as separators and the percentage present and their size controls the number and size of the cells and air spaces.

The sheet so produced is characterized by great strength and resistance to tearing, due to the interlacing and intermeshing relationship of .the comminuted cork and fibers. Moreover, because of this interlacing and intermeshing structure, a very remarkable flexibility is obtained, the fibers apparently being hinged or pivoted upon the respective cork particles. The inherent resilient quality of the cork is made available in the completed web to the desired extent, since its resiliency is not affected by the saturant which does not penetrate into the many closed cells of the particles. The compressibility of the web is enhanced by the presence of the air cells in the sheet.

a I have discovered that a web of cellular or matted form so produced will retain all of these fundamental and desirable characteristics if saturated with a binder, or preferably a binder and a plasticizer.

In the saturating process, by reason of the capillarity ofthe web due to the multitudinous air spaces, cells and voids, a very complete permeation of the formed web is obtainable, thereby uniting the cork and fibers throughout the sheet and at the same time improving its flexible characteristic; Due to the cellular structure, the product is rendered more resilient and the optimum value of the cork is obtained.

Care must be exercised in the selection of saturants, since their purpose is to permeate the cellular structure of the web and not only preserve the strength, flexibility and compression and re-bound thereof, but enhance these qualities without modifying the essential nature of the web. I have found that a most satisfactory product is obtained by introducing the web so formed into a bath of glue and glycerine and thereafter cooling the rmeated web to j ell the glue without freezmg it. Typical glueswhich may be used are those of well known commercial variety made from hides or bones and known as animal, hide, or bone glues. The web is then passed through a bath of formaldehyde which tans the glue and renders it waterproof, i. e. insoluble in water. Where I specify formaldehyde, it will be understood that paraformaldehyde may be used with a slower rate of reaction on the glue. The web is then led over the usual drying racks and rolled for commercial distribution.

By reason of the saturating treatment, the surfaces of the fibers and cork particles are coated or encased with the saturant, and thereby the product is rendered oil and waterproof. Atthe same time, the loosely matted web loses none of its inherent characteristics, since the presence of the glycerine in the flexible formaldehyde treated glutinous adhesive enhances the propertieswhich are characteristic of the web. The bath of glue and glycerine may comprlse, for example, one art of glue, e. g. bone glue, three and onehal parts of glycerine, and seven and one- V half parts of water. The formaldehyde solution may consist of one part glycerine, one

art formaldehyde, and six parts water.

ecause of the capillarity of the web, due to its innumerable interstices, the permeation or saturation is complete, regardless of the thickness of the sheet and, consequently, the plasticizer and adhesive are active throughout the entire body of the material. This result has heretofore been unattainable, except where the sheets were relatively thin, but I have found that by producing the loosely matted structure, and utilizing a saturant which tends to preserve or enhance the resiliency of the formed web, the thorough permeation and the desired characteristics are obtainable in the final product.

This treatment is to be distinguished from the use of body -or filler materials which modify or change the essential characteristics of the matted body. This body remains after the treatment, a web consisting essentially, i. e., substantially exclusively, of inter-mixed cork and fiber with-a binder. As is well known, cork cannot be impregnated, and its internal structure is not changed by the web impregnating material. The use of cork, therefore, is to be distinguished from the use of various compositions of material either with or without cork, such as sponge, tanbark, etc., all of which absorb a saturant of the character described.

While I have indicated that it is the completed web which is treated, in some instances it may be desirable to treat the cork and fibers with a binder in the beater; it is possible also to use the plasticizer in the beater.

It is interesting to observe that in the festooning or drying of the web on the racks, it gives no evidence of cracking or creasing such as is encountered with the conventional products consisting exclusively of paper fibers.

In referring to fibers, I mean a fiber element long enough to contribute tearing strength and resistance in the finished prodnot by interlacing with each other and enmeshing and holding the separating particles of cork. The fiber should be long enough to produce an absorbent paper quickly permeable to the saturants. Jute, rope, hemp, sisal, craft pulp fibers, cotton, linen, and long wood pulp fibers, as well as absorbent alphacellulose wood pulp fibers have all been found satisfactory. As stated, these fibers are mixed in a heater with the comminuted cork to produce the pulp which is subsequently felted on the paper making machine.

The comminuted cork may consist of a shredded material commercially available, or cork dust of varying sizes and granulated cork, as known in the trade.

With reference to the size of the cork granules, I prefer granules of a size which may be termed effective. The cork granules to be effective should not exceed in cross-section the desired thickness of the finished sheet, nor should they be smaller in cross section than the cross sectional diameter of the fibers. Finer cork than this will act as a filler, thereby preventing the formation of voids and also will be lost to a large extent in the paper making process; likewise smaller particles would be ineffective in acting as separators and hinges about which the fibers can flex. I have used successfully to 150 mesh and 30 to 50 mesh.

Instead of or in addition to glycerine as a plasticizer, I have foundthat sulphonated castor oil is satisfactory.

When referring tothe binder in the specification and claims as being Waterproof, I mean by waterproof, substantially water insoluble, since glue, even when treated with formaldehyde, has hygroscopic tendencies and is not entirely resistant to the absorption of water.

With respect to the waterproof binder,

plained below that by.flexible, I mean ability to withstand sharp creasing or folding without cracking.

As is understood, the glue and adhesive (casein) mentioned, resists the action of and are, therefore, insoluble in oils and gasoline with which gasket material frequently comes in contact. It may, therefore, be said that the binder used is not only waterproof, but it is insoluble in, .and not attacked physically or chemically by mineral oils.

. and is a paper-like product.

The web before its introduction to the satura-nts is characterized by innumerable air cells, voids and interstices thoughout. The cork has the action of a separator and, as stated, not only are the fibers interlaced with each other, but the cork particles are likewise enmeshed within the fibers toproduce the voids and interstices. In this manner, the sheet is rendered flexible and porous, and can be thoroughly saturated.

While I have indicated a preference for a long fibered material, quite clearly I may use in some cases, fiber in short form.

In-referring in the claims to compressibility and re-bound, I mean resilience which includes both compressibility and rebound. These are inherent qualities of the cork, and the cork is present in suliicient quantity in the web to impart the same characteristics to the web. Variation in the percentage and size of the cork particles will control the compressibility and flexibility.

The web is flexible, and by flexible, I mean the fibers are caused to hinge or pivot about the cork granules, thereby permitting the web to be sharply creased or folded without cracking.

It will be clear that the resultant product of my invention is heat insulating, and nonshrinking. a

It is a further attribute of the invention that the character of the voids and, therefore, of the cellular structure of the web, may be controlled by the size and percentage of the cork granules by volume in the web. That is to say, the comminuted cork is present in large enough volume to determine the character of the sheet.

Thus, I am enabled to produce products having the desired characteristics in varying degrees. For example, I may employ by weight of cork and 30% by weight of fibers to produce a very flexible and very resilient article. An article having less flexibility, but greater strength is obtained when 30% by weight of cork is used with 70% by weight of fibers.

The sheet may be of varying thickness as desired, in accordance with the purpose for which the material is intended.

I claim:

1. Resilient and flexible sheet material having a body mass consisting of comminuted cork and fibres in interlaced relation, and a flexible binder permanently incorporated in the mass, said binder being resistant to the action of either Water or mineral oils.

2. Resilient and flexible sheet material having a body mass consisting of comminuted cork and fibres in interlaced relation, and a plasticized, flexible binder permanently incorporated in the mass, said binder being resistant to the action of either water or mineral oils.

3. Resilient and flexible sheet material having a body mass consisting of comminuted cork and fibres in interlaced relation, and a waterproofed flexible glutinous binder permanently incorporated in the mass.

4. Resilient and flexible sheet material having a body mass consisting of comminuted cork and fibres 1n interlaced relation, and a waterproofed. glutinous binder and a plasticizer permanently incorporated in the mass.

5. Resilient and flexible sheet material having a body mass consisting of comminuted cork and fibres in interlaced relation, and a tanned glutinous binder and a plasticizer incorporated in the mass.

-6. Resilient 'and' flexible sheet material having a body mass consisting of comminuted cork and fibres in interlaced relation, and a formaldehyde treated glutinous binder and a plasticizer incorporated in the mass.

In testimony whereof I aflix my signature.

ELMER C. SCHAOHT. 

